Bahrain has been plagued by pro-democracy protests for more than two years. They caused the 2011 race to be cancelled, although it went ahead last year.

There have been calls leading up to the race for it to be cancelled but Bahraini rulers are determined for the lucrative event to go ahead.

Bahrain's Crown Prince Salman al-Khalifa told Reuters that more than 15,000 people visited the circuit on Friday and more were expected on Sunday, despite the unrest. He dismissed the suggestion the government was using the race to paper over human rights abuses.

Many journalists have been barred from entering Bahrain during the even.

The ITV News crew said they had valid media visas but were asked to leave after filing a report on Thursday.

"Our news team were on assignment with visas approved by the Bahraini authorities," a spokeswoman for ITV News told the UK newspaper.

"Having filed a report last night [Thursday], they were stopped while filming this morning and taken to a local police station for discussions with officers. They have since been asked to leave the country, which they are in the process of doing."